Disabled DROP and SURVIVE modes.

THD::vers_update_trt, trx_t::vers_update_trt, trx_savept_t::vers_update_trt:
Remove. Instead, determine from trx_t::mod_tables whether versioned
columns were affected by the transaction.

handlerton::prepare_commit_versioned: Replaces vers_get_trt_data.
Return the transaction start ID and also the commit ID, in case
the transaction modified any system-versioned columns (0 if not).

TR_table::store_data(): Remove (merge with update() below).

TR_table::update(): Add the parameters start_id, end_id.

ha_commit_trans(): Remove a condition on SQLCOM_ALTER_TABLE.
If we need something special for ALTER TABLE...ALGORITHM=INPLACE,
that can be done inside InnoDB by modifying trx_t::mod_tables.

innodb_prepare_commit_versioned(): Renamed from innodb_get_trt_data().
Check trx_t::mod_tables to see if any changes to versioned columns
are present.

trx_mod_table_time_t: A pair of logical timestamps, replacing the
undo_no_t in trx_mod_tables_t. Keep track of not only the first
modification to a persistent table in each transaction, but also
the first modification of a versioned column in a table.

dtype_t, dict_col_t: Add the accessor is_any_versioned(), to check
if the type refers to a system-versioned user or system column.

upd_t::affects_versioned(): Check if an update affects a versioned
column.

trx_undo_report_row_operation(): If a versioned column is affected
by the update, invoke trx_mod_table_time_t::set_versioned().

trx_rollback_to_savepoint_low(): If all changes to versioned columns
were rolled back, invoke trx_mod_table_time_t::rollback_versioned(),
so that trx_mod_table_time_t::is_versioned() will no longer hold.

Both bits DATA_VERSIONED will be set in prtype if the column
is system-versioned. The bits will be 0 for normal unversioned
columns. For the special columns identifying the logical start
and end times of versions, only one bit will be set:
DATA_VERS_START or DATA_VERS_END.

create_table_info_t::create_table_def(),
prepare_inplace_alter_table_dict(): Set prtype |= DATA_VERSIONED
for system-versioned columns.

dfield_t::is_version_historical_end(): Determine if a data tuple
field is_version_end() and contains a timestamp in the past
(not TRX_ID_MAX).

dtype_t, dict_col_t: Add the accessors
is_versioned(), is_version_start(), is_version_end().

trx_id_max_bytes[]: The bit pattern of TRX_ID_MAX, for use with
memcmp().

Merge branch '10.3' into trunk

Related to #212.

Extra update of sys_trx_start removed [#87].

Windows platform is suffered with this problem.

Big endian checksum is needed to workaround 10+ years old bug, where checksum
was calculated incorrectly on big endian hardware. We can still checksum such
tablespaces using software implementation of CRC32.

- make hp_mask an inline function (short and called 16 times)
- Simplify hp_search. Biggest benefit is for doing key lookup
  without a matching row. Matching rows may be a bit slower, but
  is offseted by having hp_mask inlined.

The non-persistent UPDATE_TIME for InnoDB tables was not being
updated consistently at transaction commit.

If a transaction is partly rolled back so that in the end it will
not modify a table that it intended to modify, the update_time will
be updated nevertheless. This will also happen when InnoDB fails
to write an undo log record for the intended modification.

If a transaction is committed internally in InnoDB, instead of
being committed from the SQL interface, then the trx_t::mod_tables
will not be applied to the update_time of the tables.

trx_t::mod_tables: Replace the std::set<dict_table_t*>
with std::map<dict_table_t*,undo_no_t>, so that the very first
modification within the transaction is identified.

trx_undo_report_row_operation(): Update mod_tables for every operation
after the undo log record was successfully written.

trx_rollback_to_savepoint_low(): After partial rollback, erase from
trx_t::mod_tables any tables for which all changes were rolled back.

trx_commit_in_memory(): Tighten some assertions and simplify conditions.
Invoke trx_update_mod_tables_timestamp() if persistent tables were
affected.

trx_commit_for_mysql(): Remove the call to
trx_update_mod_tables_timestamp(), as it is now invoked at the
lower level, in trx_commit_in_memory().

trx_rollback_finish(): Clear mod_tables before invoking trx_commit(),
because the trx_commit_in_memory() would otherwise wrongly process
mod_tables after a full ROLLBACK.

TODO:
- Make get_thd_memroot() inline
  - To do this, we need to reduce dependence of include files, especially
    so that sql_class.h is not depending in item.h

Added schema check logging messages.

Warnings cleanup in vtmd.cc
Stale thd->vers_update_trt after rollback to savepoint fix